Fix for: Basic support for :set statusline #1350

Hi Jared,

please review my fix. 

I add 2 new settings: 
* set laststatus=[Number] - 0 means off and some other value means on.
* set statusline=[Message] - Message will be, as it is, showed.  
Can we add the same FontSize and FontFamily bindings as the other TextBlock?  If this is better done as a template I'm good with that as well.